Cordierite–mullite coating for SiCf/SiC composites

A glass of suitable composition for coating of SiCf/SiC composites has been developed. The resulting coating is a crystalline cordierite-mullite material. The SiCf/SiC composites were coated by a simple and low cost slurry technique: a slurry made of glass powder and ethanol was put on the as-received SiCf/SiC composite and heat treated at 1180 °C for 1 h in order to obtain a uniform, pore-free and crystalline coating through the “glass–ceramic method”. The thermal analysis could not reveal any residual glass transition in the obtained coating material and the melting point of the crystalline phases formed in the coating during the coating process (cordierite, 2MgO–2Al2O3–5SiO2 and mullite, 3Al2O3–2SiO2 rate of 3:1 wt. %) was measured at about 1430 °C.